Mixed DPI support please


I just purchased a new Dell XPS13 and a 28" 4K monitor to go with it. I really wish that I could manually set the DPI for each and have them remembered. I don’t even care if they are ever in use at the same time (that is, applications don’t need to know how to display on both at the same time). However, if I could plug in the external monitor and have the DPI for that monitor remembered and scaled appropriately I would really appreciate it.